Using XML documentation comments

A while ago I read an excellent book called The Pragmatic Programmer. One of the main themes throughout the book was the DRY principle. DRY stands for Don’t Repeat Yourself. I’ll blog about that another time, as talking about it now would be a violation of the DRY principle later. Anway, the authors of the pragmatic programmer suggest that in order to avoid repetition in different forms where possible code should document itself.

Visual Studio offers a tool to help you do this. You can decorate your code with special comments by typing in three forward slashes. One of those tools is the xml comments feature that helps you comment functions in a useful way.

This is really handy for two reasons. The first is because it gives you a helpful structure, and a reminder about what sort of information you might want to put in your comments (However sometimes good naming of variables make the comments a little redundant). The really nice thing about documenting your code in this way is that visual studio can use this to populate intellisense, so people using this method don’t even have to find the definition to read these comments. They just pop up as and when they might be required.

Two examples of intellisense using my comment to deliver information when it might be needed

As I said, good method and function names can sometimes render such comments redundant, but sometimes they are invaluable.

Intellisense being really useful

Take this example using the .net Random class. This comment reassures me that if I ask for a random number and pass in 0 and 5, then there is a chance I will get 0, rather than the lowest value possible being 1.

Additionally, by checking a box in a project’s build menu you can get visual studio to create an xml file of your project. This could be used to create documentation for the internet automatically, using tools such as Sandcastle.